Especially in the context of devices for manipulating specimen slides that automatically carry out working steps when handling a specimen slide, it is often necessary for components of the respective device to be correctly oriented with respect to one another. Such components contact the specimen slide directly and/or contact the samples to be brought into contact with the specimen slide or further elements to be brought into contact with the specimen slide. For correct positioning of the specimen slide and/or of the sample or the further elements, the components of the device should be correctly oriented with respect to one another. Such devices for manipulating specimen slides include, in particular, a unit for automatically applying a biological sample onto a specimen slide, a unit for automatically cleaning a biological sample, a unit for automatically staining a biological sample arranged on the specimen slide, and/or a unit for automatically covering a biological specimen, arranged on the specimen slide, with a coverslipping agent and/or a coverslip.
DE 101 44 048 A1 describes an apparatus for manipulating specimen slides and coverslips. In this, a coverslip is picked up with the aid of a pickup unit guided via an actuation arm, and is placed onto a desired position on the specimen slide. Automatic apparatuses of this kind for the application of coverslips onto specimen slides are also referred to as “coverslippers.” The coverslips serve in this context to cover a prepared specimen present on a specimen slide. A prepared specimen of this kind is preferably a biological sample, such as a histological section. The coverslips are thin, preferably having a thickness of approx. 0.17 mm, and are made available in a stack. In order to pick up a coverslip from the stack, the pickup unit must therefore be exactly positioned with respect to the stack in order to pick up the topmost coverslip of the stack. In the same fashion, upon placement of the coverslip onto the specimen slide, the coverslip or the pickup unit having the coverslip must be exactly positioned with respect to the specimen slide. If deviations occur during positioning of the coverslip and the pickup unit, the risk exists that the glass of the coverslip and/or of the specimen slide may break.
DE 10 2005 020 426 A1 describes a coverslipping machine for applying coverslipping agent and a coverslip onto a specimen slide. Here, in particular, the means for picking up and positioning the coverslip on the specimen slide must be oriented exactly with respect to a holder of the specimen slide so that exact positioning of the coverslip can be carried out, and furthermore in order to avoid damage to or destruction of the coverslip.
In coverslipping machines, it is usual to orient the basic device itself in three dimensions with the aid of auxiliary means for leveling a base frame of the basic device, and additionally to orient an actuation element positionable with respect to the base frame, or a holding element for the actuation element, relative to the base frame, so that these elements are likewise oriented exactly in three dimensions with reference to a horizontal plane. The actuation arm, or a mount for the actuation arm, is usually connected to the base frame, and auxiliary alignment means can be provided in order to orient the actuation arm relative to the base frame of the coverslipping machine.
Problems similar to those with the coverslipping machine also occur with other devices for manipulating specimen slides with which preferably automatic preparation of a sample for microscopic investigation is carried out.